feat: Phase 3 - Partners API (5 endpoints + 2 helpers)

- GET /api/v1/partners/stats/ - total, active, pendingKyc, highRisk counts
- GET /api/v1/partners/ - paginated list with status/kyc/type/search filters
- GET /api/v1/partners/:id/ - full detail with events, kycDocuments, dealTerms, ledger
- PATCH /api/v1/partners/:id/status/ - suspend/activate partner
- POST /api/v1/partners/:id/kyc/review/ - approve/reject KYC with reason

Helpers: _serialize_partner(), _partner_kyc_docs()
Status/KYC/type mapping: backend snake_case to frontend capitalised values
Risk score derived from kyc_compliance_status (high_risk=80, approved=5, etc.)
All views IsAuthenticated, models imported inside methods

admin_api/urls.py

@@ -12,4 +12,10 @@ urlpatterns = [
     path('dashboard/revenue/', views.DashboardRevenueView.as_view(), name='dashboard-revenue'),
     path('dashboard/activity/', views.DashboardActivityView.as_view(), name='dashboard-activity'),
     path('dashboard/actions/', views.DashboardActionsView.as_view(), name='dashboard-actions'),
+    # Phase 3: Partner endpoints
+    path('partners/stats/', views.PartnerStatsView.as_view(), name='partner-stats'),
+    path('partners/', views.PartnerListView.as_view(), name='partner-list'),
+    path('partners/<int:pk>/', views.PartnerDetailView.as_view(), name='partner-detail'),
+    path('partners/<int:pk>/status/', views.PartnerStatusView.as_view(), name='partner-status'),
+    path('partners/<int:pk>/kyc/review/', views.PartnerKYCReviewView.as_view(), name='partner-kyc-review'),
 ]